Sheet folding machines



June 20,1961 G. SMITH.

SHEET FOLDING MACHINES 3 Sheets-Sheet 1 Filed May 12, 1959 June 20, 1961 G. SMITH SHEET FOLDING MACHINES 3 Sheets-Sheet 2 Filed May 12, 1959 June 20, 1961 G. SMITH SHEET FOLDING MACHINES 3 Sheets-Sheet 3 Filed May 12, 1959 United States aten 2,989,305 SHEET FOLDING MACHINES Geoffrey Smith, 46 E. India Dock Road, London E14, England, assignor of one-half to James Armstrong & Company Limited, London, England, a British com- Filed May 12, 1959, Ser. No. 812,728 8 Claims. (Cl. 270-68) This invention relates to sheet folding machines or machines for folding bed sheets or other fabric sheets. The invention is primarily intended for use in laundries, for folding bed sheets after they have been delivered from the calender in a condition ready for return to the customers.

The invention has for its object the provision of an improved sheet folding machine, and the invention consists broadly of a machine for folding bed sheets or other fabric sheets, comprising a belt conveyor on which the sheets are fed in succession, in such a way that they hang down on each side of the belt, and means for holding back the forward edge of each sheet, so that, by the convey-ing action of the belt, said forward edge becomes progressively doubled back, and for subsequently releasing said forward edge, so that, thereafter, the doubled sheet as a whole, still hanging down on each side of the belt is conveyed by said belt.

The word belt occurring in the above paragraph and throughout the claims is to be understood as covering belts of all suitable kinds including chain-like structura, and as covering not only a single belt but also a plurality of separate relatively narrow belts side by side, which again may be of any suitable form such as wires or chains.

In order that the invention may be the more clearly understood, a sheet folding machine in accordance therewith will now be described reference being made to the accompanying drawings wherein:

FIGURE 1 is a side elevation of the machine, shown partly in section;

FIGURE l2 is a similar side elevation, to a larger scale of a portion of the machine;

FIGURE 3 is an end elevation looking from the left of FIGURE 2;

FIGURE 4 is a plan of the parts shown in FIGURES 2 and 3 FIGURE 5 is a partly diagrammatic view illustrating the electro-pneumatic control system employed in the machine;

FIGURE 6 is a side view, to a large scale, of a switch employed in the machine;

FIGURE 7 is an end view of the same.

Referring to the drawings, the sheets 1 (FIGURES 4, 6 and 7) are fed in succession from the calender 2 on to a belt conveyor having a rather narrow belt 3, in such a way that the sheets hang down equally on each side of said belt. This conveyor conveys the sheets on to a second conveyor which forms a continuation of the first and has a similar belt 4. Said belt 4 travels at a higher speed than the belt 3, in order to ensure that any ruckles which the sheet may have acquired in passing on to the belt 3 will be smoothed out.

At a suitable distance forwardly from the calender 2, a sheet-folding mechanism is provided which comprises two roughly U-shaped or bridge shaped folding elements 5 and 6, each formed of a bent sheet metal strip. One (5) of said folding elements is of larger dimensions than the other (6), and said elements are both rotatable about the same axis XX, passing through both legs of both elements near the ends thereof, with Patented June 20, 1961 The axis XX passes transversely and horizontally a little above the belt 4, and the legs of the folding elements 5 and 6 are symmetrically on each side of said belt. Normally, the position is as shown in FIGURES 2, 3, 4 and the full line position of FIGURE 1, said folding elements being in a roughly horizontal plane, with the middle portions forwardly of the axis XX and passing over the belt 4. q

The middle portion of the inner folding element 6 has a flange 7 bent over rearwardly from its lower edge, assuming the position to be normal, said flange extending right over the belt 4 and beyond each side thereof. The outer folding element 5 has two lugs 8 extending downwards from its lower edge, one on each side of the belt 4, said lugs, at a level beneath said belt being bent over rearwardly at 9, and having soft pads 10 of, say, rubber mounted on said rearwardly bent portions 9. The outer folding element 5 also has a central flange 11 bent over rearwardly from its upper edge, said flange 11 overhanging, and being in contact with, the upper edge of the inner folding element 6. Thus the mechanism which has been described can be said to be comprised of a pair of jaws on each side of the belt which grip the front edge portions of each sheet which depend at the sides of the belt. Each pair of jaws is constituted by one of the lugs 9 with its pad 10 and the appertaining end portion of flange 7.

As each sheet, hanging over the belt 4, as above described, approaches the forward portions of the elements 5 and 6, the leading edge portion of the sheet is spread somewhat by passing over two guides 12 so that it passes over the two pads 10. At the same time, in response to the sheet reaching the appropriate position, the outer folding element 5 is rotated counter clockwise about the axis XX by means which will be hereinafter described.

This operation is timed so that the two pads 10 engage underneath the front i.e. the leading edge portion of the sheet before the latter has reached the middle or transverse portion of the folding element 5. Said pads 10 then raise said front edge portion of the sheet until said pads engage the underside of the flange 7 (with said front edge portion of the sheet in between) and, thereafter, the folding element 5 carries the folding element 6 with it aroundthe axis XX. The movement of said folding element 6 around said axis is subject to a friction drag, as will be hereinafter described, and thus, as said two folding elements 5 and 6 rotate together counter clockwise around said axis XX, the said front edge portion of the sheet will be nipped fairly tightly between the pads 10 on the one hand and the flange 7 on the other, and said front edge portion of the sheet will be folded back. The said elements 5 and 6 rotate through approximately and then stop, and thus the said front edge portion of the sheet is folded or doubled back roughly two right angles and is accordingly held at level a little above the belt 4. The position now is that what was at first the front edge of the sheet is folded back and held stationary, still, of course, hanging down on each side of the gripper constituted by the pads 10 and the flange 7, i.e. on both sides of the belt 4 outside the hanging-down iLe. the depending portion'of the major portion of the sheet still on the belt, but the belt is still moving forwards and conveying with it said major portion of the sheet. The con sequence is that more and more of the sheet becomes folded back until, by the time the rear i.e. the trailing edge of the sheet comes level with what was originally the front edge, the sheet is folded double.

At approximately this point, as will hereinafter appear, the outer folding element 5 is rotated clockwise back to the original position shown in FIGURE 2. During the initial part of such rotation, the pads are separated from the flange 7. The flange 11 of the folding element 5 then engages the folding element 6 and thereafter said folding element 6 is carried back with said folding element 5 to the original position. As soon as the pads 19 are separated from the flange 7 the edge of the doubled back portion of the sheet is left simply resting on said flange 7, and it accordingly slides off said flange 7 either before or after the latter commences to move, and said doubled back portion falls down onto the portion of the sheet still on the belt 4. The doubled sheet as a whole, still hanging over the belt 4, is now conveyed forwards.

At a position a little further forwards, a second sheetfolding mechanism similar to the first is provided, as will be clear from FIGURE 1, so that the sheet is again doubled, and finally the sheet is delivered from the forward end of the conveyor on to a slide 13 of the same width as the belt on which the twice doubled sheet is supported still hanging down on each side of said slide. The sheet has now been twice doubled by lateral folds, and, by virtue of its hanging down on each side of the slide 13, it is, in effect, again doubled by a longitudinal fold, and it can be removed by hand in that condition.

Describing now in more detail the manner in which the folding elements 5 and 6 are mounted and operated, the outer folding element 5 has one of its legs secured fast, by means of a boss 14 to a trunnion 15, and has its other leg secured fast by means of a boss 16 to a trunnion 17. Said two trunnions and 17, which are, of course, coaxial with the axis XX, rotate in bearing holes in portions of the main frame 18 of the machine. The trunnion 15 has its extremity projecting beyond its bearing hole, and, mounted fast on said extremity is a sprocket wheel 19 over which passes a chain 20 whose two ends depend down vertically. One end of said chain 20 is connected to the upper end of a vertical piston rod 21 whose lower end is connected to a piston in a vertical cylinder 22, mounted on a part of the fixed frame 18. The other end of said chain 20 is connected to the upper end of a vertical tension spring 23 whose lower end is connected to a part of said fixed frame. Thus, when air under pressure is admitted to the upper end of the cylinder 2, the piston moves to the lower end of its stroke and thereby, through the chain 21, rotates the sprocket wheel 19, and therefore the outer folding element 5, counter clockwise to the folding position, this operation also stretching the spring 23. When air is exhausted from the upper end of the cylinder 22, the spring 23 operates to return the sprocket wheel 19 and the outer folding element 5 to the normal position.

The folding element 6 has one of its legs secured fast to a boss 24 which rotates freely on the trunnion 17, and has its other leg secured fast to a brake drum 25 which rotates freely on the trunnion 15. Two brake shoes 26 engage said brake drum 25 on opposite sides thereof. said brake shoes being pivoted at points 27 to a part of the fixed frame 18, and being biased about said pivot points towards each other by means of helical springs 28 coiled on a coupling rod 29 which passes through holes in said brake shoes, each spring, as clearly shown in FIGURE 2, being in compression between a respective, brake shoe and a nut 30 screwed on the extremity of said coupling rod.

Thus, as before stated, the rotation of the inner folding element 6 takes place in both directions in opposition to a friction drag.

Describing now, with reference to FIGURE 5 the manner in which the supply of compressed air to, and its exhaust from, the cylinder 22 is effected, a pipe 31, connected to the upper end of the cy1inder22 is connected to two branch pipes 32 and 33. The branch pipe 32 leads to the expansible air chamber 34 of an electric switch 35 which closes when compressed air is admitted to said air chamber and opens when compressed air is exhausted from said air chamber. The branch pipe 33 leads to an air valve 36 which is controlled by a solenoid 37 in such a way that, when said solenoid is energised, the branch pipe 33 is connected to a pipe 38 which is in communication with a source of compressed air supply, and, when said solenoid is de-energised, said branch pipe 33 is connected to exhaust and the pipe 38 is closed. Two switches 39 and '40 are provided arranged alongside the belts 3 and 4 at longitudinal positions as shown in FIGURE 1. Each of these switches is normally open and is closed by being overlaid by each sheet as it is carried along by the belts. These switches 39 and 40 are connected in series with each other, and with the solenoid 37 across a source of electric supply L1, L2, and the switch 35 is connected in parallel with the switch 40.

It will now be seen that, normally both switches 39 and 40 are open; the solenoid 37 is deenergised; the supply pipe 38 is cut off, and the top end of the cylinder 22 is connected to exhaust. Thus the piston will be at its upper end and both folding elements 5 and 6 wilLbe at their normal positions. As each sheet is conveyed from the calender 2, first along the belt 3 and then along the belt 4, its forward edge will first overlie the switch 39 and close it. This however, will, for the moment be without effect. Subsequently said forward edge will reach, and overlie, the switch 40, and said switch 40 will also close, and thereby a circuit will be established, from the source L1, L2, through the solenoid 37. The supply pipe 38 will accordingly be connected both to the chamber 34 and to the upper end of the cylinder 22, and thus the switch 35 will close and the piston in the cylinder 22 will move downwards, causing the folding elements 5 and 6 to rotate clockwise and thus double back the forward portion of the sheet as heretofore described.

It will be noticed that the doubling back of the forward portion of the sheet will cause the switch 40 to open, but, owing to the switch 35 being now closed, this will be without effect.

When the rear edge of the sheet reaches the appropriate position, it will uncover the switch 39 and the latter will open, thereby deenergising the solenoid 37. Consequently the valve 36 will be operated to close the supply pipe 38 and connect the pipe 33 to exhaust, thereby opening the switch 35 and connecting the upper end of the cylinder 22 to exhaust, so that the spring 23 will operate to return the folding elements 5 and 6 to the normal position. The folded sheet will now be conveyed onwards as before described.

The second sheet-folding mechanism is in every respect similar to the first, and no further description thereof is therefore necessary.

It will be seen that both belts are driven by a common electric motor 41. Thus said motor drives two equal pulley wheels 42 and 43, the latter at a higher speed than the former. The belt 3 runs over, and is driven by, the pulley wheel 42 and the belt 4 runs over, and is driven by the pulley wheel 43.

It will be seen that the belt 3, throughout the region where it supports the sheets, slides over a supporting underplate 44, and the belt 4 in like manner slides over a supporting underplate 45, both underplates being, of course, supported from the main frame 18 of the machine. The aforesaid guides 12 are mounted on the underplate 45. The conveyors and also the folding elements are covered by a protective cover 46, and this, at its end nearest the calender 2 carries a pair of idler rollers 47 which press yieldably on the belt 3 and thus afford a positive grip for the forward end of the sheet as this leaves the calender.

Turning now to FIGURES 6 and 7, these illustrate one of the switches 39, 40 (say the switch 39). This switch is a mercury switch and comprises a container 48 having a body of mercury therein. Said container is supported beneath the belt 3 by means of two opposite coaxial pointed members 49, in such a way as to be rotatable about the common axis of said members, which axis is transverse to said belt. Said members 49 are in turn carried by a bracket 50 supported from the underplate 44. A finger 51 extends upwards and at an angle outwards from the container 48, and said container and finger are biased to the normal position illustrated, at which'said finger extends up just past the side edge of the belt 3. This is the open positionof the switch. When the forward edge of the sheet 1 arrives, it engages said finger 51 and rocks the same, together with the container 48, to the chain dotted position of FIGURE 6, i.e. the closed position of the switch, and the sheet retains said finger and container at this position so long as it is overlying the switch. As soon as the rear end of the sheet passes, the finger and container return to the normal open position of the switch.

The above described sheet-folding machine may be modified in various ways. For example, in place of the air cylinders, hydraulic cylinders or electric solenoids could be employed.

I claim:

1. In a machine for folding flexible fabric sheets, the combination comprising a conveyor belt, means feeding the sheets in succession forwardly along said belt, said belt being relatively narrow as compared with the width of the sheets whereby the sheets are supported by and depend from each side of said belt, jaw means located at each side of said belt in such position as to engage the leading edge of said sheet along the corresponding depending portion thereof, means actuating said jaw means upon engagement by said leading edge of the sheet for gripping said leading edge at said depending portions and arresting its forward motion whereby said leading edge is progressively folded back over the remaining portion of the sheet as the latter continues its forward travel along said belt, and means releasing said jaw means from said leading edge of the sheet when the trailing edge thereof reaches approximate alignment with said leading edge thereby leaving the sheet folded on said belt and depending at each side thereof.

2. A folding machine as defined in claim 1 wherein said jaw means are constituted by two pairs of jaws, said pairs of jaws being located respectively laterally outward from each side of said belt and which further includes guide means engaging the leading edge of those portions of the sheet which depend at each side of said belt for spreading and guiding the same into their respective pairs of jaws.

3. A folding machine as defined in claim 2 wherein each said pair of jaws comprises an under jaw and an over jaw between which said leading edge portion of the sheet is fed, and means raising said under jaw to grip said leading edge portion of the sheet between said under jaw and over jaw.

4. A folding machine as defined in claim 1 and which further includes a stationary slide extending beyond the delivery end of said conveyor belt as a continuation of the path of said conveyor belt, whereby said conveyor belt operates to transfer said folded sheet onto said slide and with the said depending portions thereof also depending at each side of said slide.

5. In a machine for folding flexible fabric sheets, the combination comprising a conveyor belt, means feeding the sheets in succession forwardly along said belt, said belt being relatively narrow as compared with the width of the sheets whereby the sheets are supported by and hang down on each side of said belt, a first jaw-supporting structure rotatable about an axis transverse to said belt, a second jaw-supporting structure rotatable about the same axis, each of said jaw-supporting structures having a normal angular position, two under jaws carried by said 6 first supporting structure and positioned laterally to each side of said belt and forwardly from said axis at the normal position of said first supporting structure, two over jaws carried by said second supporting structure and positioned respectively above said under jaws at the normal position of said second supporting structure, guide means along said belt for spreading laterally away from said belt the leading edge portions of each sheet which overhang the sides of said belt, whereby said leading edge portions are fed by said belt above said under jaws and beneath said over jaws, means actuated upon presentation of said leading edge portions of the sheet between said under jaws and over jaws for thereupon rotating said first supporting structure about said axis in the direction such that said under jaws are first raised to grip said leading edge portions between said under jaws and said over jaws, whereafter said second supporting structure is rotated about said axis by said first supporting structure to a given position, and the leading edge of the sheet is thereby folded back and held for further folding back owing to the conveying action of said belt, means controlled by the trailing edge portion of the sheet for subsequently rotating said first jaw-supporting structure in the return direction to its normal position, and co-engaging means on said jaw-supporting structures effective upon a rotation of said first jaw-supporting structure in said return direction to its normal position to first separate said under jaws from said over jaws thereby releasing said folded back leading edge portion of the sheet and then to carry said second jaw-supporting structure back to its normal position.

6. A folding machine as defined in claim 5, and which further includes drag means for resisting the rotation of said second jaw-supporting structure, whereby adequate pressure is ensured between said under jaws and said over jaws during rotation of said first supporting structure in said first-named direction, and the separation of under jaws from said over jaws is ensured at the commencement of the rotation of said first jaw supporting structure in said return direction.

7. A folding machine as defined in claim 5 wherein said means for controlling the rotation of said first jawsupporting structure comprise means for biasing said first jaw-supporting structure to its normal position, a pneumatic cylinder and piston, means coupling said position to said first jaw-supporting structure whereby, upon admission of compressed air to said cylinder said first jaw supporting structure is rotated to said given position, a winding, first and second normally open switches in series with said winding spaced along the track of said conveyor, said first switch being closed upon the leading edge of the sheet passing a given position on said conveyor and said second switch being closed upon the leading edge of the sheet passing a second given position on said conveyor following said first position, and said first switch being reopened upon the trailing edge of said sheet passing said first given position, an air valve opened upon energization of said winding to admit compressed air to said cylinder, and a third switch, in shunt with said second switch, said third switch being closed by compressed air in response to the opening of said valve.

8. In a machine for folding flexible fabric sheets, the combination comprising a conveyor belt, means feeding the sheets in succession forwardly along said belt, said belt being relatively narrow as compared with the width of the sheets whereby the sheets are supported by and hang down on each side of said belt, a first jaw-supporting structure rotatable about an axis transverse to said belt, a second jaw-supporting structure rotatable about the same axis, each of said jaw-supporting structures having a normal angular position, two under jaws carried by said first supporting structure and positioned laterally to each side of said belt and forwardly from said axis at the normal position of said first supporting structure, two over jaws carried by said second supporting structure and positioned respectively above said under jaws at the normal position of said second supporting structure, guide means along said belt for spreading laterally away from said belt the leading edge portions of each sheet which overhang the sides of said belt, whereby said leading edge portions are fed by said belt above said under jaws and beneath said over jaws, means actuated upon presentation of said leading edge portions of the sheet between said under jaws and over jaws for thereupon rotating said first supporting structure about said axis in the direction such that said under jaws are first raised to grip said leading edge portions between said under jaws and said over jaws and for then rotating said two supporting structurm together in the said direction to a given position, whereby the leading edge of the sheet is folded back and held for further folding back owing to the conveying action of the belt, means controlled by the trailing edge portion of the sheet for subsequently rotating said first jaw-supporting structure in the return direction and thereby separating said under jaws from said over jaws and releasing said folded back leading edge portion of the sheet, and for then rotating both jaws in said return direction back to their normal positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,650,821 Howlett Sept. 1, 1953 2,740,627 Woodward et a1 Apr. 3, 1956 2,811,350 Cran et a1. Oct. 29, 1957 2,815,946 Gram Dec. 10, 1957 FOREIGN PATENTS 587,593 Great Britain Apr. 30, 1947 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent Note. 2,989,305 June 2O 1961 Geoffrey Smith It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 56 after "separation of! insert said line 44', for "position" read piston Signed and sealed this 1st day of August 1961s (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

